Most game developers don't have an experimental psychologist on staff. Then again
Valve isn't like most game developers. Gamasutra talked with Valve's own psychologist Mike Ambinder about one of the things Valve has done to make its game different than norm; features made specifically to assist disabled gamers.
Some of those features include a colorblind mode, closed captions and subtitles, in-game pauses for single player campaigns and others. Ambinder states that such features also benefit able gamers as well. He states, "For example, both groups of gamers benefit from the ability to pause
Left 4 Dead 2 if they need to take a break or escape from the action, and the addition of subtitles allows all gamers to process the in-game dialogue/sound effects through an alternative visual medium if that is their preference."